First, we've got population. The world today has 6.8 billion people. That's headed up to about nine billion. Now, if we do a really great job on new vaccines, health care, reproductive health services, we could lower that by, perhaps, 10 or 15 percent.
https://www.ted.com/talks/bill_gates_innovating_to_zero/transcript?language=en
Bill Gates has said that the healthier a population is the less children people decide to have, by choice. So it's quite clear in this quote that he's talking about increased health resulting in fewer people having kids or people having fewer kids which would, while there would still be an increase, cause the population to increase not quite as much.
Now while that's all perfectly logical and is a completely valid explanation based on what he's actually said, how all he's said fits together, and without any "oh he actually means this" it's probably still all a pile of bullshit meant to hide the fact that Gates wants to not only reduce population growth through much more evil means but most likely also wants to cause a massive depopulation event.
We all agree this is what these people want, I just don't agree this quote is "muh 100% proof that evil billionaires want to kill everyone and talk about it in the open and people/sheep still follow whatever they say". Alone the quote in this thread is a massive nothing-burger that proves absolutely nothing one way or the other.